function [XD,YD]=p_line(lx,rx)
% p_line: Return vertices of a horizontal line
%
% SYNTAX:
%   [XD,YD] = p_line(lx,rx)
%   [XY] = p_line(lx,rx)
%   Return vertices of a horizontal line in interval [lx,rx] of x-axis

%   Author: Hongbin Ma
%   Last updated: 2009-6-2 with MATLAB 6.5
%   Problems or suggestions? Email me: mathmhb[at]163.com

XD=[lx,rx];
YD=[0,0];
if nargout<2,
    XD=[XD;YD]';
end;
